1. Field of the Invention
The invention relates to improvements in eccentric rotary valve for flow control.
2. Description of the Prior Art
U.S. Pat. No. 3,494,589 discloses a control valve in which the valve plug closure member is movable in a rotatory sense about an axis which is directed rectangularly to the valve housing and which is displaced in relation to the axis of the valve housing. More specifically, the valve comprises a spherical closing face or plug which forms one seating surface of the valve and a ring-shaped valve seat in the valve housing which forms another seating surface. The valve plug is connected with a pivot axis via a flexible arm. The flexible arm provides a limited amount of annular displacement or cocking of the valve to insure complete seating of the spherical closing face with the ring-shaped seat face of the valve housing.
To provide a flexible arm has proved to be disadvantageous insofar as this flexibility of the arm only can be achieved by weakness of the arm. This weakness of the flexible arm comprises the danger of breaking with increasing of operation cycles. A further disadvantage is to be seen in the fact that the pressure of the fluid medium is acting in a sense which is releasing the sealing connection between the valve body and the valve seat. Because of the flexible arm the acting pressure may lift up the valve plug from the valve seat.